Widely Tunable Narrow-Linewidth Lasers Using Self-Injection DBR Lasers

Linewidth Narrowing of Mutually Injection Locked Semiconductor Lasers with Short and Long Delay

“…Moreover, mutual phase-locking in mutual injection locking provides a unique mechanism for linewidth narrowing. The intrinsic linewidth of lasers mutually coupled by fiber link is in the order of 100 Hz, narrower thañ kHz obtained in fiber-link based self-injection configuration [15,16]. In this work, frequency noise reduction mechanisms, dependence on coupling parameters and locking conditions are investigated theoretically and experimentally, demonstrating mutual injection locking as a simple and practical method to compress laser linewidth.…”

“…For example, in classical Littrow [42] or Littman [43] configuration, the mode is selected by grating and FP cavity. The Vernier effect in multiple ring resonators [11][12][13]16] is also employed to realize single mode selection. However, stable single-mode lasing state in mutual injection locking is a result of coupling between two oscillators [30,31], which can lase independently without mutual optical injection.…”

“…As for self-injection or external cavity, a fraction of light emitted from the gain material is fed back through a low loss external cavity, hence the laser linewidth is reduced by increased photon lifetime. Recent research centers on the realization techniques of self-injection, such as low loss Si [11,12] or Si3N4 [13,14] ring resonator, fiber components based feedback circuit [15,16], assembled confocal Fabry-Perot (FP) cavity [17] and CaF2 cavity [18]. These structures rely on high Q cavity or multiple mode selection components.…”

“…Locking condition and dependence of laser linewidth on coupling parameters in both regimes are studied, confirming mutual injection locking as a practical method for linewidth narrowing. For the short-delayed integrated lasers, a linewidth narrowing factor of 13 is demonstrated and sub-MHz linewidth is achieved, while for the long-delayed lasers coupled by fiber link, the intrinsic linewidth is reduced to sub-100 Hz.Recent research centers on the realization techniques of self-injection, such as low loss Si [11,12] or Si 3 N 4 [13,14] ring resonator, fiber components based feedback circuit [15,16], assembled confocal Fabry-Perot (FP) cavity [17] and CaF 2 cavity [18]. These structures rely on high Q cavity or multiple mode selection components.In this work, we propose and demonstrate a simple but effective approach to linewidth narrowing based on mutual injection locking (MIL) of semiconductor lasers.…”

Low-linewidth and tunable single frequency 1x2 multimode-interferometer-Fabry-Perot laser diode

“…Grating-based distributed feedback (DFB) lasers and distributed Bragg reflector (DBR) lasers have demonstrated robust single longitudinal mode performance and broad wavelength tunability thus gaining wide interest, while the required fabrication complexity of nanometer dimensional gratings and material regrowth limits the yield and increases the cost. In addition, the free-running linewidth reported for DFB and DBR laser devices is typically in the 1-5 MHz range which restricts their applications in coherent optical communications systems and ultra-high resolution spectroscopy applications [3][4].…”